DIY CO2 regulation

[motoman]

I built a DIY Co2 using a 2 litre pop bottle and a mixture of 1 cup sugar, 1 tbls of traditional yeast and about 3/4 bottle of water. I have a little valve to control the Co2 but I'm very concerned about the build up of C02 and the bottle popping or something. I haven't read anywhere of this happening or of people letting the bottle breath for a day first, should I do this? There just seems to be a lot of C02 coming out and I need to have the valve almost completely closed in order to only get about 1 bubble every 10 seconds or so. Any advice?

[dpatte]

i also make CO2 the same way, for my 75Gal.

Put a T in the middle of your tubing and a valve to bleed of CO2 to the air there.

[BigDaddy]

Actually, with DIY CO2, you need to modify your receipe to generate the right amount of CO2 for your needs.

If you are generating too much CO2, then cut back on the yeast in your receipe.

More yeast = more production
More sugar = longer production

Of course, that's a very vague statement, but you get the idea.

PS - That amount of yeast is pretty high unless you have a HUGE tank.  The most common receipe is 1/4 to 1/2 tsp yeast to 2 cups sugar.

[motoman]

Ok both replies are much appreciated. I'll get a bleeder valve tomorrow. I'm using the DIY on a 20 gal. Just from today my plants are already pearling. Any suggestions on recipe mixes for a 20 gal? I'm thinking halfing the yeast. Also should I disconnect of shut off the CO2 at night? I know that the plants won't use it but will it hurt anything?

[BigDaddy]

You can run CO2 overnight, and for DIY it is recommended, simply because it will take all night to replenish the CO2 back up to optimal values by lights on.

CO2 levels over 30ppm can be detrimental to fish health.  Take a pH and kH reading just before lights on (when your CO2 will be at its highest) to ensure it isn't building up too much at night.  If it is... cut back on the yeast in your receipe.

PS - Modified my earlier post for the "norm" which is what you should be using for a 20 gallon.

Edit:  With the right mix of yeast and sugar, you won't need the bleeder valve.

[motoman]

Great I'm going to disconnect and change my recipe and see how that works. One other question since I can't find my notes anymore. How do I get the Co2 reading using PH and KH? Thanks a bunch folks!

[BigDaddy]

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

[pegasus]

I'll probably never gonna have plants but I read your post and I'm amazed to see all that dedication and knowledge. What I'd like to know is how many days will his DIY last before he needs to replenish it?

[BigDaddy]

Typically every 2 weeks

[dpatte]

im not sure about two things.
1) I find my CO2 lasts about 4 weeks
2) Im not sure adding more yeast at startup increases speed of production (except initially) I thought that however much yeast you add it multiplies quickly to a stasis point within a few hours. I find i always get the same production within one day no matter how much yeast I add.

[BigDaddy]

When I was still doing DIY (I'm pressurized now), my batch would produce CO2 for well over the 2 week mark, probably close to a month.  However, after two weeks, the production had petered off enough that I wasn't reaching optimal CO2 values.  In a medium light tank, that's not much of a worry, but my high light tank needed the full amount of CO2 to fend off algae blooms.

[gvv]

OK, I have some general questions about CO2 which came to me after I read the article "Measuring CO2 levels in a Planted Tank". Can somebody explain me, as I don't know whether to start with CO2 injection or no?

1. Does it mean that I need to add CO2 in values from  the green fields of table? Just for example, if I have pH=6.2 GH = 0.5 and KH =0.5 I should begin adding 15ppm of CO2, which later become 3-4 ppm nevertheless?
2. What is the point to add CO2 if the ammout of CO2 in water, accoding to this article will be going to its saturation level: "Again, after a few hours, the CO2 level will equalize, and the water will end up with 3-4ppm CO2"? Or we just trying to give plants more CO2 while it is not dissipate from the water?
3. Should I continue adding CO2 at night even at this time plants are not using CO2, but O2. Is it safe to add more CO2 (it will dissipate nevertheless?)?
4. Also, I found some articles where people saying that if you have "overcrowded" tank, fish will produce enough CO2. Is it really so?

Thanks in advance!

[BigDaddy]

OK, I have some general questions about CO2 which came to me after I read the article "Measuring CO2 levels in a Planted Tank". Can somebody explain me, as I don't know whether to start with CO2 injection or no?

1. Does it mean that I need to add CO2 in values from  the green fields of table? Just for example, if I have pH=6.2 GH = 0.5 and KH =0.5 I should begin adding 15ppm of CO2, which later become 3-4 ppm nevertheless?

You want to continuously inject CO2 to MAINTAIN at least 15ppm of CO2 in the water.

2. What is the point to add CO2 if the ammout of CO2 in water, accoding to this article will be going to its saturation level: "Again, after a few hours, the CO2 level will equalize, and the water will end up with 3-4ppm CO2"? Or we just trying to give plants more CO2 while it is not dissipate from the water?

We are just adding CO2 to benefit the plants during their photoperiod.

3. Should I continue adding CO2 at night even at this time plants are not using CO2, but O2. Is it safe to add more CO2 (it will dissipate nevertheless?)?

Some people run it continuously, some turn it on and off.  CO2 values should never exceed 30ppm, or you could have fish starting to suffocate

4. Also, I found some articles where people saying that if you have "overcrowded" tank, fish will produce enough CO2. Is it really so?

No, fish respiration will never produce the optimal amounts of CO2 in a planted tank.

Thanks in advance!

Your welcome!

[trollop]

I have just built a CO2 system using 4 inch pvc pipe.
It is capped at one end with the other end capped with a screw on cap. The cap has a brass air nipple to allow for the CO2 release. The unit is about 3 foot tall so is capable of producing quite a bit of CO2. This should also be tall enough so that no yeast scum will make its way up to the exit point and muck up the tank.
I was thinking of about 4 cups of sugar and a packet of yeast.
Do you think 4 cups is enough?
I was aslo thinking of using this bendable air stone from Wal-mart. It is 22 inches long and will put out a lot bubbles.
Any thoughts for this end?

David

[BigDaddy]

Airstones are very very poor diffusers.  The majority of the CO2 will simply bubble to the surface and escape.

[trollop]

The other option I was toying with would be basicaly a bell shape etc type unit under the water with the bottom open.
This would give more Co2 surfuce contact.........

[BigDaddy]

Yes... a bell is a very simple diffuser.

Just ensure the surface area of the bell can keep up with the production of CO2, otherwise it will overfill and you'll get CO2 escaping from the bell.

I tried a small tupperware container once, but it didn't really do the job well.  Something semi-spherical would provide the largest surface area for its given amount of space.

[motoman]

Quote: The most common receipe is 1/4 to 1/2 tsp yeast to 2 cups sugar.

Big Daddy, do you mean 1/2 tablespoon or should I use 1/2 a teaspoon? I just wanted to clairify, thanks.

[aSmallFish]

tsp = teaspoon

[dpatte]

tsp = teaspoon , tbsp = tablespoon

arent you glad we are going metric instead of sticking with this this arcane system?

[motoman]

Ok, I just wanted to make sure you didn't make a mistake. I took your advice and used 2 cups of Sugar and 1/2 tsp of yeast. Mixture is much better. Slowed the Co2 production way down so I can at least control it. Thanks for all the help folks! My tank should be growing very soon.  

P.S. Anyone take a look at my plant problem post? Not sure if I need a better/different fertilizers or what.